Method for quenching a gas stream in the production of vinyl chloride monomer

Abstract

A method and apparatus for quenching a gas stream in the production of vinyl chloride monomer includes the use of a knock back condenser and a plurality of column fractional distillation trays disposed within the quench column, and a liquid stream of 1,2-dichloroethane, vinyl chloride, and hydrogen chloride may be removed from the bottom column fractional distillation tray.

I claim: 
     
       1. A method of quenching a gas stream comprising vinyl chloride, hydrogen chloride, and unreacted 1,2-dichloroethane produced by the pyrolysis of 1,2-dichloroethane and containing undesired byproducts of pyrolysis, comprising the steps of: (a) providing a quench column, having an upper and a lower end, the lower end of the quench column containing a quantity of quench liquid;   (b) introducing the gas stream directly into the quench liquid to cool the gas stream to cease the pyrolysis of the 1,2-dichloroethane and minimize the formation of additional byproducts whereby 1,2-dichloroethane, vinyl chloride, and hydrogen chloride vapors rise from the quench liquid;   (c) providing a plurality of column fractional distillation trays, with at least an upper column fractional distillation tray and a bottom column fractional distillation tray, within the quench column above the quantity of quench liquid;   (d) passing the 1,2-dichloroethane, vinyl chloride, and hydrogen chloride vapors upwardly through the plurality of column fractional distillation trays;   (e) introducing liquid 1,2-dichloroethane, vinyl chloride, and hydrogen chloride into the upper end of the quench column, above the plurality of column fractional distillation trays;   (f) removing 1,2-dichloroethane, vinyl chloride, and hydrogen chloride vapors from the upper end of the quench column; and   (g) removing a liquid stream of 1,2-dichloroethane, vinyl chloride, and hydrogen chloride from the bottom column fractional distillation tray.   
     
     
       2. The method of claim 1, wherein the liquid, 1,2-dichloroethane, vinyl chloride, and hydrogen chloride are introduced into the upper end of the quench column by providing a knock back condenser in the upper end of the quench column above the column fractional distillation tray, and partially condensing the rising 1,2-dichloroethane, vinyl chloride, and hydrogen chloride vapors. 
     
     
       3. The method of claim 1, wherein the liquid, 1,2-dichloroethane, vinyl chloride, and hydrogen chloride are introduced into the upper end of the quench column by providing a horizontally disposed condenser above the quench column; partially condensing the rising 1,2-dichloroethane, vinyl chloride, and hydrogen chloride vapors; and introducing the liquid 1,2-dichloroethane, vinyl chloride, and hydrogen chloride from the horizontally disposed condenser into the upper end of the quench column. 
     
     
       4. The method of claim 3 including the step of flowing the liquid 1,2-dichloroethane, vinyl chloride, and hydrogen chloride into the upper end of the quench column by only utilizing the force of gravity, whereby no pump is utilized to introduce the liquid 1,2-dichloroethane, vinyl chloride, and hydrogen chloride. 
     
     
       5. The method of claim 1, including the step of removing from the bottom of the quench column a portion of the quench liquid containing the undesired byproducts of pyrolysis. 
     
     
       6. The method of claim 5, including the step of filtering out the undesired byproducts of pyrolysis, from the removed quenched liquid.